Grocery store profits aren't larger than any other industry. Nor are they larger than in the past. Large grocery store chains do not have high profit margins. Sure, the total profit may be large if you run 1000 grocery stores.

What do you mean by they are the wealthiest in the nation? None of the richest people in the world built their fortunes on groceries?

Price fixing is a phenomenon. Anti trust is a policy agenda. What entity would carry out the proposed agenda, when the parties supposedly fixing are in different countries?

How long did the fixing agreement last successfuly? DRAM has famously gone through booms and busts where supply outstripped demand and led to very cheap prices and no profits.

OPEC worked about as well as any cartel. Could you give an example of a cartel maintaining their position without heavy government help? Even the drug cartels in mexico, with extreme willingness to coerce, cannot maintain a monopoly and have competed drug prices in the US down heavily! If you consider memory a cartel, then it has only remained so by... drastically improving the quality and reducing the cost of its product? Hardly a problem.

> None of the richest people in the world built their fortunes on groceries?

The Waltons (Walmart) aren't some of the richest people in the world?

> What entity would carry out the proposed agenda, when the parties supposedly fixing are in different countries?

Few can, to be fair. The US and the EU are some of the few that can due to the size of the markets underneath them. A company getting excluded from their markets is enough for them not to want to risk anti-trust enforcement.

China can to some extent as well, which is why you see the likes of Hollywood bending over backwards to meet Chinese standards in media. It's a large enough market that they don't want to miss out.

> How long did the fixing agreement last successfuly?

I see no reason they wouldn't have gone on indefinitely. The only thing that ultimately ended them and caused the busts was antitrust enforcement.

> Could you give an example of a cartel maintaining their position without heavy government help?

Modern examples are few and far between, and that's because the historic examples failed to use their money to buy off enough government officials to cement their positions.

Standard Oil would be an example of this. They did spend money to avoid being regulated, but they didn't ultimately use that to push policies and laws to cement their position in the market. They simply bought out competitors as they rose up.

Bell Labs/AT&T is another example that didn't use their influence to cement their position. They got their monopoly fairly naturally. The closest you could argue is they got utilities access laws passed by the government.

An even older example would be the East India Company. They became so big that they actually took over land and established themselves as a government. Basically the only reason they fell was because of an armed rebellion.